Semiconductor device

Abstract

The second conductivity type thin film includes: a high-concentration layer having a first impurity concentration; a first electric field relaxing layer continuous to the high-concentration layer at an outer circumference of the high-concentration layer, the first electric field relaxing layer having a second impurity concentration lower than the first impurity concentration; a second electric field relaxing layer continuous to the first electric field relaxing layer at an outer circumference of the first electric field relaxing layer, the second electric field relaxing layer having a third impurity concentration lower than the second impurity concentration; and a first electric field diffusion layer continuous to the second electric field relaxing layer at an outer circumference of the second electric field relaxing layer, the first electric field diffusion layer having a fourth impurity concentration lower than the third impurity concentration.

The invention claimed is: 
     
       1. A semiconductor device having a surface outer circumferential portion, the semiconductor device comprising:
 a first conductivity type thin film; 
 a second conductivity type thin film provided on the first conductivity type thin film;
 the second conductivity type thin film including 
 a high-concentration layer having a first impurity concentration, 
 a first electric field relaxing layer continuous to the high-concentration layer at an outer circumference of the high-concentration layer, the first electric field relaxing layer having a second impurity concentration lower than the first impurity concentration, 
 a second electric field relaxing layer continuous to the first electric field relaxing layer at an outer circumference of the first electric field relaxing layer, the second electric field relaxing layer having a third impurity concentration lower than the second impurity concentration, and 
 a first electric field diffusion layer continuous to the second electric field relaxing layer at an outer circumference of the second electric field relaxing layer, the first electric field diffusion layer having a fourth impurity concentration lower than the third impurity concentration; and 
 
 a channel stop layer located at an ultimate end of the surface outer circumferential portion, the channel stop layer being connected to the first electric field diffusion layer, the channel stop layer having an impurity concentration higher than an impurity concentration of the first conductivity type thin film, the channel stop layer having a first conductivity type, and 
 a second electric field diffusion layer located between the first conductivity type thin film and the second conductivity type thin film, the second electric field diffusion layer having an impurity concentration higher than the impurity concentration of the first conductivity type thin film, the second electric field diffusion layer having the first conductivity type. 
 
     
     
       2. The semiconductor device according to  claim 1 , further comprising a plurality of embedded regions each located in the first electric field diffusion layer and having a second conductivity type, wherein respective widths of the plurality of embedded regions become smaller toward an outer circumference of the semiconductor device. 
     
     
       3. The semiconductor device according to  claim 1 , comprising a silicon carbide semiconductor element provided with a trench, wherein
 the first conductivity type thin film includes a drift region of the silicon carbide semiconductor element, and 
 the second conductivity type thin film includes a body region of the silicon carbide semiconductor element. 
 
     
     
       4. The semiconductor device according to  claim 1 , comprising a silicon carbide semiconductor element provided with a trench, wherein the second electric field diffusion layer includes a trench current diffusion layer of the silicon carbide semiconductor element.